You won't find much mass spec here. I think they only used it to confirm they'd purified phosphorylated ubiquitin from the unmodified variant. Most of the work here is NMR (i.e., I'm not real confident in any interpretation I could draw from their results, so I won't say too much about them) but pH is also involved here -- yikes -- 'cause it affects the charge on the phosphate group (making me just a little concerned that this isn't something we think about in terms of phosphoproteomics when we chemically enrich them and drop them in formic acid -- are we losing tons of biologically relevant information -- and could our technology ever possibly get us to it -- maybe neutral or negative phosphoproteomics?!?) And the longest sentence ever award goes to....

This makes sense, though, right? And maybe it is something to think about. Because not only does the phosphorylation change the 3D structures here, but so does the charge on the phosphorylations. Great paper and something I'll be thinking about all day!